Protein Expression Analysis in the Resurrection Plant, Selaginella lepidophylla

Abstract

Understanding the mechanisms used by plants to survive stressful environmental conditions, such as water deficits due to drought is vital to the development of genetic engineering strategies to improve or retain agricultural productivity in the face of increasing environmental insults, changes in rainfall patterns and global warming. Desiccation tolerance is a rare adaptive response of resurrection plants to exist in environments with intermittent drought by entering into a state of metabolic inactivity, wherein vegetative structures are preserved under air-dried conditions. Upon rewatering, these plants resume their metabolic activities and repair any damage that occurred while in the dry state. The mechanistic basis of desiccation tolerance can be better understood by studying it using integrative functional genomics approaches including transcriptomics, proteomics, and metabolomics. In this study, protein expression patterns within fully hydrated and desiccated tissues of Selaginella lepidophylla were investigated using a gel-based proteomics approach. A phenol-based protein extraction protocol was optimized for S. lepidophylla tissues by including a series of washing steps with methanol, acetone and ether in order to remove membrane lipids and polyphenolics. Protein expression profiles were then compared using two-dimensional difference polyacrylamide gel electrophoresis (2D-DIGE). The 2D-DIGE analysis revealed that 130 proteins that were differentially expressed with 107 proteins showing increased abundance and 23 showing decreased abundance in the dry state compared with the hydrated state. Late embryogenesis abundant and heat shock proteins and reactive oxygen scavenging enzymes were overrepresented in the dried state.